bus210_appendix_e[1]

Legacy systems are the software and the hardware of a company’s IT system.  Companies put large amounts of money into legacy systems. 
Mainframe computers were first developed in the year 1951.  When these mainframe computers were first built they used vacuum-tube technology.
The microprocessor is also known as a computer on a chip.  They were created in the year 1970.  The microprocessors were the start of desktop computers.
PCs are known as personal computers.  These are well known today as desktop computers.  The personal computer was created in the year 1976.  PCs became well known in the 1980’s.
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